Stage 1
OEM-Plus Under-Seat Subwoofer Enclosure for GM Trucks
Stage 1 is the foundation of the CB Customs lineup — a clean, OEM-plus under-seat enclosure designed specifically for 2019–2026 GM trucks. This option is for customers who want real bass without sacrificing factory appearance or interior function.
Built in-house and engineered around the GM under-seat area, Stage 1 gives you a proper enclosure solution — not a generic prefab box shoved under the seat.
Fitment
Built Specifically for 2019–2026 GM Trucks
- Fits 2019–2026 GM trucks (under-seat fitment).
- 3D-modeled for precise under-seat fitment with an OEM-plus install.
- Rear seat functionality remains completely factory.
- Designed to look clean and intentional once installed.
Enclosure Specs
Internal Dimensions & Clearances
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Total Air Volume
1.88 ft³ total air space.
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Mounting Depth
5.45 inches.
Note: Actual depth may vary based on subwoofer magnet size.
Note: Actual depth may vary based on subwoofer magnet size.
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Woofer Clearance
2.25 inches from the bottom of the enclosure to the floor.
What’s Included
What Comes with Stage 1
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Custom Under-Seat Enclosure
Precision-built enclosure engineered specifically for GM under-seat fitment.
Designed for clean output and long-term reliability.
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Standard Black Carpet Finish
Stage 1 comes standard in high-quality black carpet for a factory-clean look.
Optional color-matched vinyl upgrades are available.
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Plug-and-Play Terminal Cup
Includes our custom 3D-printed CB Customs terminal cup for clean, reliable,
and easy amplifier connection.
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Optional Loaded Configuration
Stage 1 is sold unloaded by default. You can choose to add subwoofers and receive
the enclosure fully loaded and ready to drop in.
Performance
What to Expect
Stage 1 is built for clean, controlled bass that integrates properly with factory or upgraded audio systems. It’s a big improvement over stock, while keeping the install subtle and OEM-looking.
Power handling and final impedance depend on subwoofer selection if you choose a loaded option. If you want help picking subs or matching an amp, reach out and we’ll point you in the right direction.
Built by CB Customs
Craftsmanship, Lead Time & Warranty
- Hand-built in Weatherford, Texas using CNC-cut panels and in-house assembly.
- Built to order — lead time is confirmed after purchase.
- Lifetime craftsmanship warranty on the enclosure.
- Real support — direct help before and after purchase if you have questions.
Compare CB Customs Stages
All stages are engineered for real performance. The higher the stage, the more show-level details (acrylic, lighting, and visual flex) you get on top of the sound.
Overall look
Stage 1
Clean OEM-plus enclosure, no acrylic, no lighting.
Stage 2
OEM-plus with a single acrylic accent panel.
Stage 3
Full custom acrylic face & design details.
Stage 5
Full show-truck treatment with acrylic window, RGB lighting & premium cosmetics.
Acrylic & windows
Stage 1
No acrylic.
Stage 2
Standard front acrylic accent.
Stage 3
Acrylic details + window (design-dependent).
Stage 5
Large viewing window + internal acrylic bracing.
Lighting
Stage 1
No lighting.
Stage 2
Optional add-on (front lighting).
Stage 3
Standard internal / perimeter lighting. Underglow optional.
Stage 5
Standard RGB lighting with under-seat glow.
Finish
Stage 1
Premium carpet or vinyl in OEM-matched style.
Stage 2
Upgraded vinyl & accent details.
Stage 3
Multi-texture, stitched and layered show-style finish.
Stage 5
Highest level finish: layered vinyl, acrylic, and color-matched details.
Pre-wired & install
Stage 1
Pre-wired & plug-and-play cup.
Stage 2
Pre-wired & plug-and-play cup.
Stage 3
Pre-wired, subs mounted, quick drop-in.
Stage 5
Pre-wired, bench-tested & ready to flex.
Best for
Stage 1
Clean daily driver, hidden bass.
Stage 2
OEM-plus with a touch of custom.
Stage 3
Show-ready daily build.
Stage 5
Full platinum, SEMA-level flex.
Quick rule of thumb: Stage 1 = clean. Stage 2 = clean + accent. Stage 3 = full custom show piece.
Stage 5 = platinum, no-compromise flex piece.
Questions?
Still not sure which stage or setup to go with?
Shoot us a text or call at (682) 516-3358, email sales@cbcustoms.net, or reach out below with your truck year and goals.